It has been discovered that the medical outcome for a patient suffering from severe brain trauma or from ischemia caused by stroke or heart attack or cardiac arrest is improved if the patient is cooled below normal body temperature (37° C.). Furthermore, it is also accepted that for such patients, it is important to prevent hyperthermia (fever) even if it is decided not to induce hypothermia. Moreover, in certain applications such as post-CABG surgery, it might be desirable to rewarm a hypothermic patient.
As recognized by the present application, the above-mentioned advantages in regulating temperature can be realized by cooling or heating the patient's entire body using a closed loop heat exchange catheter placed in the patient's venous system and circulating a working fluid such as saline through the catheter, heating or cooling the working fluid as appropriate in an external heat exchanger that is connected to the catheter. The following U.S. patents, all of which are incorporated herein by reference, disclose various intravascular catheters/systems/methods for such purposes: U.S. Pat. Nos. 6,881,551 and 6,585,692 (tri-lobe catheter), U.S. Pat. No. 6,551,349 and U.S. Pat. No. 6,554,797 (metal catheter with bellows), U.S. Pat. No. 6,749,625 and U.S. Pat. No. 6,796,995 (catheters with non-straight, non-helical heat exchange elements), U.S. Pat. No. 6,126,684, U.S. Pat. No. 6,299,599, U.S. Pat. No. 6,368,304, and U.S. Pat. No. 6,338,727 (catheters with multiple heat exchange balloons), U.S. Pat. No. 6,146,411, U.S. Pat. No. 6,019,783, U.S. Pat. No. 6,581,403, U.S. Pat. No. 7,287,398, and U.S. Pat. No. 5,837,003 (heat exchange systems for catheter), U.S. Pat. No. 7,857,781 (various heat exchange catheters).
As understood herein, such catheters often cannot be customized for each individual patient when manufactured, and therefore must be made in a standard size. As further understood herein, this observation means that, in some patients, unused space may exist in the blood vessel beyond that needed to ensure adequate blood flow around the catheter.